Striker plate for perforators



sebi-'21, 1954 J. A. BUTLER 2,689,609

$TRIKER PLATE FOR PERFORTOR4 Filed May 14, 1951 mfg Patentec Sept. 21, 1954 UNITED STATES PATENT OFFICE STRIKER PLATE FOR PERFoRA'roRs James A. Butler, Glencoe, Ill.

Application May 14, 1951, Serial No. 226,253

Claims.

This invention relates to machines for perforating or embossing sheets of leather and similar materials, and more particularly to "backing plates for such machines.

The present invention has parti-cular utility when Iapplied -to th-e perforation of sheets. of leather during the-manufacture of shoes and, accordingly, the invention will be described in reference to this particular application. However, it is to be understood that the invention is applicable to other types of forming operations and to other types of material.

Leather used in forming designs on shoes is perforated by driving die pins through the leather while the leather is being supported. In order to obtain a clean and yclear out perforation, it is necessary to provide a resilient or iiexible backing or striking yplate for the die pin-s. Heretofore, according to one practice, paper has been used as the backing m-aterial, the paper being disposed between the leather sheet and the support for the leather sheet. As the die pins pass through the leather, they impinge upon the paper thereby achieving complete severance of the perforated leather pieces from the remainder of the leather sheet. Since the ends of the die pins are sharp, the paper is perforated and, therefore, it is necessary to use a new area of paperfor each perforating operation if a uniform and clean cult perforation is to be obtained each time.

For this reason, large rolls of paper have been provided heretofore, and means for moving the paper after each perforating operation have also been provided to insure that a fresh, unperforated strip of paper was available for each leather perforating operation. The `cost of the paper is relatively large, the storage of the bulky roll of paper is costly and the perforations in the leather sheet are not always uniform and clean cut.r In addition, the sharpened ends of the die pins pass through the paper and impinge upon the metal backing plate and thereby the cutting edges of the die pins are dulled.

In another form of perforating machine used heretofore, a wooden block has been used as the backing member or striking plate against which the die pins impinge. This arrangement also includes means for changing the area of the wooden block contacted by the die pins. It has been -found that perforations made with this machine are not well formed and are not uniform. The die pins also tend to become worn and dull quickly.

It is, therefore, an important object of the present invention to provide an improved apparatus for perforating leather sheets; more speneed be replaced infrequently.

Yet another yobject of the invention is to provide a backing member which is more economical in operation and in initial cost.

Still another object of the invention is to provide an improved backing member which gives better and more clean cut perforations and which preserves the life of the perforating die pins.

A further object of the invention is to provide v. an improved apparatus for removing and changing the surface of the backing member which is exposed to the perforating dies.

These and other objects and advantages of the invention will be better understood from the following description when taken in conjunction with the accompanying drawings.

ing wherein like reference numerals have been In the drawused to indicate like parts throughout :z

Fig. 1 is an elevational View with certain parts broken away showing an improved backing mem-A ber and a mounting therefor made in accordance with and embodying the principles of the present invention;

Fig. 2 is a perspective view of the support plate upon which the improved backing member is mounted;

Fig. 3 is a perspective view of the pulley on which the improved backing member is mounted; Fig. 4 is a perspective view of the improved backing pad or member made in accordance with the present invention;

Fig. 5 is an enlarged perspective view of the insert which is molded in the improved backing plate;

Fig. 6 is an exploded perspective view of the die plate, the stripper plate, and the leather sheet to be perforated;

Fig. 7 is an enlarged View in vertical section through the assembled support plate, pulley and backing pad; and

Fig. 8 is an enlarged view in vertical section substantially as seen in the direction of the arrows along the lines 8-8 of Fig. 6, the die plate, stripper plate and backing pad being shown in assembled relationship.

Referring now to Fig. l, there is shown a perforating machine made in accordance with and embodying the principles of the present invensacoe 3 cation in a pair of guides I2 and I4. The head I8 is shown in the upper position in Fig. 1.

Mounted on the lower face of head l is a support plate I6. Plate I6 is rectangular in shape and is provided with an aperture I8 in the center thereof and a plurality of peripherally disposed apertures 28 which receive bolts 22 to mount plate I6 on head I0. A circularly shaped pulley 24 is rotatably mounted on the support plate I6 by means of a bearing member 26. More specifically, the aperture I8 in plate I6 has an outwardly directed groove formed around the upper edge thereof to receive an outwardly extending flange 28 formed on the bearing member 26. .The bearing member 26 and the grooved aperture I8 are such a size that the bearing member 26 freely rotates upon support plate I6. The pulley 24 is attached to the bearing member 26 by a plurality of bolts 36 which pass through apertures in bearing member 26 and screw into the body of pulley 24. The heads of the bolts are counter-sunk in the bearing member 26 so that all of the members are iiush with the upper surface of support plate I6.

The centerl of bearing member 26 is provided with a downwardly extending threaded stud 32 which serves to interconnect pulley 24 with a backing pad or striking plate 34. More specifically, the striking plate 34 is circular in shape and has a diameter substantially equal to the diameter of pulley 24. There is embedded in the upper surface of striking plate 34 a circular insert 36 which has a threaded aperture in the center thereof to receive the threaded stud 32. The periphery of insert 36 has a plurality of serrations or teeth 3l formed thereon to provide positive engagement between the insert 36 and plate 34.

The striking plate 34 is connected to pulley 24v by inserting the threaded stud 32 into the aperture in insert 36.

Means is provided for rotating the striking plate 34, the pulley 24 and the bearing member 26 as a unit in the form of a belt 38. There has been shown for purposes of illustration a belt 38 which is circular in cross section and which coe operates with a semicircularly shaped groove 46 formed around the periphery of pulley 24. It is to be understood, however, that other shapes of belts and grooves can be used. A prime mover (not shown) drives belt 38 preferably so that pad 34 moves in a counterclockwise direction when viewed from above. The threads on the stud 32 are cut in a clockwise direction so that rotation of the pulley 24 tends to tighten the connection between stud 32 and the insert 36 when the pulley is rotated. The direction of rotation of the pulley 24 and the direction of the thread on stud 32 can be reversed as long as both are reversed, i. e., so long as the direction of rotation of pulley 24 and the direction of the thread on stud 32 are opposite.

The movable press head I8 is mounted vertically above a base 42 on which are positioned a pair of guides 44 and 46. These guides 44 and 46 slidably receive a removable die plate 48 having a handle 58 attached to the forward edge thereof. This arrangement permits the use of a plurality of die designs as desired. Mounted in apertures 52 in the body on the die plate 48 are a plurality of die pins 54 which form the design to be perforated on a leather sheet 56 mounted upon a stripper plate 58. Pins 54 are usually circular in cross section and are provided with an aperture extending longitudinally therein and terminating in an upper sharp cutting edge 66. The pieces of leather cut by the die pins 54 pass through the apertures in the center of the die pins and drop through the apertures 52 in the die plate.

The stripper plate 58 is substantially rectangular in shape and has an area slightly less than the area of the die plate 48. Positioned at each corner of the stripper plate 58 is a post 62 which is received in aperture 64 in the corners of the die plate 46. The upper portions of the aperture 64 are enlarged to receive a coiled spring 66 which lies between the die plate 48 and the underside of the stripper plate 58. Spring 66 is so constructed as to hold stripper plate 58 adjacent the upper edges of the upstanding pins 54 when no pressure is applied to the stripper plate 58. When pressure is applied to the stripper plate 58, the springs 66 are compressed to the position shown in Figure 8.

The pins 62 are held on the stripper plate 58 by means of heads 68 which also retain light springs 'I6 on the upper surface of the stripper plate 53. The springs I8 are elongated and relatively thin whereby to occupy very small space in a vertical direction. One end of the spring l0 is engaged by the heads 68 and the other end is directed inwardly and diagonally as shown in Fig. 5. The free ends of the spring 'I8 hold the piece of leather 56 in position upon the stripper plate 58. An upraised portion l2 is attached to the upper surface of the stripper plate 58 and has a shape conforming to the inner outline of the strip of leather 58. There are also formed in the stripper plate 58 a plurality of apertures which correspond in size and position to the die pins 5A.

In operation the movable press head I8 is lifted to theV upper position as shown in Fig. 1. A suitably shaped piece of leather 56 is then tted around the upraised portion 'I2 on stripper plate 58 and the springs 18 are rotated to the position shown in Figure 5 whereby to hold the leather piece 56. The head I0 is lowered and the backing pad 34 presses against the piece of leather 56 and forces the stripper plate 58 downwardly against the action of springs 66. After the head has travelled a short distance, the cutting edge 66 of pins 54 pass through the associated apertures in stripper plate 58 and into the leather 56. Further movement of head I0 pushes pins 54 completely through the leather 56 and against the striking plate 34. The pieces of leather cut out by the die pins 54 are forced through the apertures in the die pins. The cutting edge 66 of die pins 54 are moved toward and then into the surface of the striking plate 34 to insure complete severance of the cut-out pieces of leather from the remaining portions of the piece. When head I0 is lifted, the springs 66 push stripper plate 58 upwardly and disengage the pins 54 from thestriking plate 34 and the leather piece 56.

The perforated leather piece 56 is then removed and a new piece inserted. Movement of head I0 to the upper position simultaneously rotates the pulley 24 in a counter-clockwise direction a short distance so that a new surfaceof striking plate 34 will be exposed to the action of the pins 54 during the next perforating operation. In this manner, a fresh surface of striking plate 34 is presented for each successive perforation, and the wear of the striking plate 34 is thereby distributed over sub stantially the entire surface thereof.

It will be seen from the above description of-l the operation of the perforating machine that the I bamate) backing pad 34 must be resilient and capable of deformation to permit impingement of the sharpened edge 60 of die pins 54 thereagainst without permanently harming the backing pad -34 and without dulling the cutting edges 60. It has been found that a plastic composition is a preferred material from which to manufacture plate 34. A preferred plastic from which to make striking plate 34 is made by blending the following materials: Hycar 0R25 (modified butadiene-acrylonitrile copolymer) 100 lbs.; zinc oxide 5.50 lbs.; technical stearic acid 1.50 lbs.; Philblack A 20.00 lbs.; Cumar P25 (coumarone-indene resin) 5.00 lbs.;v cotton flock #60 50.00 lbs.; Altax (benzothiazyl disulfide) 1.30 lbs.; sulfur 1.00 lb.; Cumate (cupric diethyl-dithio car- 1.00 lb.; and Durez resin #12687 (phenol-formaldehyde resin molding compound) 159.00 lbs.

These materials are thoroughly blended and slabbed off the rubber mill in sheets having a thickness of approximately '12,. The sheets are allowed to cool and then sawed into pieces about 3 x 6" and ground in a hammermill. The ground composition is placed in a compression mold of suitable shape and cured for 25 minutes at 320 F. under a pressure of about 2,000 lbs. per sq. in. The insert 36 is molded directly into one face of the striking plate. A typical plate has a diameter of i/2" and a thickness of from 0.300 to 0.312. In this size of plate the insert is preferably 3" square and has a thickness of approximately lg. It is to be understood that the plate and insert can be made in various sizes and shapes and that these examples are given only for illustrative purposes and are not to be construed as limiting the invention.

A striking plate having the above composition and made according to the procedure disclosed has the following physical properties: specific gravity of 1.32; a tensile strength of 4,400 lbs. per sq. in.; an elongation of 4%; and an impact strength, notched Izod of 2.10 ft. lb. in.; and a hardness durometer D of 75 to 82. The plate is hard yet pliable, is non-thermoplastic, and will not erode or chip. By supporting the plate 34 in the center by means of insert 36, the plate can undergo converse distortion under constant impact whereby to permit the plate to hug tightly to the pulley 24. When the ends of the die pins 54 impinge upon the surface of the plate 34, cold 110W, or mushrooming, of the plate material occurs but does not interfere with the efficiency of the plate. More specifically, the plate remains. fiat and does not tend to buckle. For example, during operation the ends of the die pins will penetrate the surface of the plate 34 about 0.003 up to maxium penetration of 0.125. The plate must not be brittle and must not undergo embrittlement if suitable backing for the die pins 54 is to be obtained.

It will be seen that there has been provided a striking plate and mounting therefor which fulfills all the objects and advantages set forth above. More specifically, a striking plate has been provided which is relatively inexpensive and which has a long useful life. The resiliency and pliability 0f the plate preserves the cutting edge on the die pins, and yet the plate has suicient hardness to give a sharp, clean perforation in cooperation with the die pins. The mounting for the plate insures that a fresh surface is presented to the die pins for each successive perforating operation and, in addition, the wear on the pad is eclualized and made uniform.

Although certain preferred structures and compositions have been shown for purposes of illustration, it is to be understood that various changes and modifications can be made in these struetures and compositions without departing from the spirit and scope of the invention. Accordingly, the invention is to be limited only as set forth in the following claims.

The invention is hereby claimed as follows:

1. In a die plate assembly for use in a perforatin'g machine, the provision of a 'backing member, a striking plate of resilient plastic material of sufcient rigidity to maintain the same in surface contact with the adjacent surface of the backing member and against which the material to be perforated is pressed, and means e 1 bedded in the striking plate for securing the same to the backing plate only at a restricted center portion thereof with the remainder of the striking plate material substantially free to radially expand and contract whereby to prevent buckling thereof and to maintain snug and substantially uniform surface contact of the striking plate with the material being perforated during the perforating operation.

2. In a die plate assembly as claimed in claim 1, wherein the said embedded securing means in the center thereof comprises an insert having coupling means cooperating with other coupling means on the backing plate.

3. In a perforating machine having a backing member to support a striking plate adapted to act against the material to be perforated and to receive the cutting edge of the perforating tool, the provision of a striking plate of resilient plastic material, and means embedded in substantially the center of said striking plate attaching the same to the backing member said center attaching means being the only support for said striking plate whereby to permit deformation of said striking plate in a direction substantially radially thereof under influence of pressure applied to the striking plate, and the plastic material of said striking plate being of sufficient rigidity to maintain the outer periphery thereof in substantially fixed axial position relative to the attaching means at the center thereof.

4. In a perforating machine as claimed in claim 3, wherein the attaching means includes an insert having a threaded aperture for receiving a complementary threaded stud member.

5. In a perforating machine as claimed in claim 3, wherein the attaching means includes an insert having a plurality of outwardly extending circumferential projections embedded in said striking plate.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 299,329 Belin May 27, 1884 876,361 Kraft et al. Jan. 14, 1908 1,063,871 Grover June 3, 1913 1,676,260 Glidden July 10, 1928 1,751,451 Smith Mar. 18, 1930 1,960,009 Holbrook May 22, 1934 2,170,646 Rosenberg Aug. 22, 1939 2,263,626 Halbig Nov. 25, 1941 2,281,877 Green May 5, 1942 2,369,643 Berger Feb. 20, 1945 2,545,045 Rosan Mar. 13', 1951 2,575,378 Bender Nov. 2 0, 1951 2,600,165 Horgan June 10, '1952 

